This invention relates generally to the field of downhole tools, and, more particularly, to downhole tools used for determining real time properties of fluids originating from subsurface earth formations.
Electric downhole tools are used for determining various properties of fluids originating from subsurface earth formations. Conventional methods of using these devices involve using the tool to first withdraw a sample of fluid from a subsurface earth formation into a sample chamber of the tool. Thereafter, the volume of the sample chamber is incrementally increased, while the device measures the pressure, volume, and temperature of the sample. These measurements provide data for calculating fluid properties, such as bubble point pressure and compressibility. Unfortunately, these conventional tools are not operable during well production, and must be removed from a wellbore prior to flowing the well.
Accordingly, the present invention is directed to overcoming one or more of the limitations of the existing devices.
An apparatus for determining real time bubble point pressure of a fluid originating from a subsurface earth formation includes a sample chamber adapted to contain a sample of the fluid. A piston in the sample chamber adjusts the volume of the sample chamber. A pressure/temperature gauge fluidicly couples to the sample chamber, and monitors the pressure and temperature of the fluid sample within the sample chamber. A controller operably couples to the piston and pressure/temperature gauge. The controller continuously monitors the pressure, temperature, and volume of the sample fluid during expansion of the sample chamber. The controller also determines the bubble point pressure of the fluid, based on the pressure and volume measurements.
According to another aspect of the present invention, the controller of the same apparatus is also adapted to determine the compressibility of the sample fluid based on the pressure and volume measurements.
According to another aspect of the present invention, a method of determining real time bubble point pressure of a fluid originating from a subsurface earth formation includes first sampling the fluid during well production. After sample collection, the volume of the sample fluid is then incrementally increased, while the pressure, temperature, and volume of the sample fluid are monitored. The bubble point pressure of the sample fluid is then extrapolated from a graph of the pressure and volume measurements.
According to another aspect of the method of the present invention, after the step of monitoring, the compressibility of the sample fluid is then determined from a graph of the pressure and volume measurements.
According to another aspect of the present invention, a system for determining real time bubble point pressure of a fluid originating from a subsurface earth formation includes a production tubing adapted to facilitate the flow of fluid to the surface. A side pocket couples to the production tubing, and contains a downhole device. The downhole device is adapted to expand a sample of fluid. The downhole device is also adapted to measure the temperature and pressure of the sample of fluid. A remote controller, at the surface or downhole, operably couples to the downhole device. The controller is adapted to monitor the temperature, pressure, and volume of the sample of fluid. The controller is also adapted to determine the bubble point pressure of the fluid based on the pressure and volume measurements.
According to another aspect of the present invention, the controller of the same system is also adapted to determine the compressibility of the fluid, based on the pressure and volume measurements.